def check_and_replace(txt):
    dangerous_words = ["黑客", "抓包", "监听", "Trojan", "窃取"]
    for word in dangerous_words:
        txt = txt.replace(word, "@_@")
    return txt
txt = '我是一名程序员，我喜欢看关于黑客的书，我想研究Trojan。'
result = check_and_replace(txt)
print(result)